Photon-counting optical-fiber sensor for the detection of ammonia in neurochemical applications

Elamari, A.; Gisin, Nicolas; Cruz, J.L.; Poitry, Serge; Tsacopoulos, M.; Zbinden, Hugo

doi:10.1016/s0925-4005(97)80190-6

Cited by 7 publications

(7 citation statements)

References 9 publications

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“…This sensor is a miniaturized version of the sensor described by Kar and Arnold (1992). The method for fabricating this sensor was similar to that described by Elamari et al (1997), with some modifications. A glass micropipette with short stem was made, using a vertical homemade puller, and its tip was broken with a diamond cutter to an inner diameter of 50 m and fire-polished.…”

Section: Methodsmentioning

confidence: 99%

Mechanisms of Glutamate Metabolic Signaling in Retinal Glial (Müller) Cells

et al. 2000

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Retinal Müller (glial) cells metabolize glucose to lactate, which is preferentially taken up by photoreceptor neurons as fuel for their oxidative metabolism. We explored whether lactate supply to neurons is a glial function controlled by neuronal signals. For this, we used subcellular fluorescence imaging and either amperometric or optical biosensors to monitor metabolic responses simultaneously from mitochondrial and cytosolic compartments of individual Müller cells from salamander retina. Our results demonstrate that lactate production and release is controlled by the combined action of glutamate and NH(4)(+), both at micromolar concentrations. Transport of glutamate by a high-affinity carrier can produce in Müller cells a rapid rise of glutamate concentration. In our isolated Müller cells, glutamine synthetase (GS) converted transported glutamate to glutamine that was released. This reaction, predominant when enough NH(4)(+) is available, was limited at micromolar concentrations of NH(4)(+), and more glutamate entered then as substrate into the mitochondrial tricarboxylic acid cycle (TCA). Increased production of glutamine by GS leads to increased utilization of ATP, some of which is generated glycolytically. Methionine sulfoximine, a specific inhibitor of GS, suppressed the stimulatory effect of glutamate and NH(4)(+) on glycolysis and induced massive entry of glutamate into the TCA cycle. The rate of glutamine production also determined the amount of pyruvate transaminated by glutamate to alanine. Lactate, alanine, and glutamine can be taken up and metabolized by photoreceptor neurons. We conclude that a major function of Müller glial cells is to nourish retinal neurons and to metabolize the neurotoxic ammonia and glutamate.

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Section: Methodsmentioning

confidence: 99%

Mechanisms of Glutamate Metabolic Signaling in Retinal Glial (Müller) Cells

et al. 2000

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“…Elamari et al (1997) used a fibre optic device to measure [NH 4 + ]. The circular extremity of the probe (diameter more than 80 μm) was positioned on the surface of a retinal slice and they show a recording in which [NH 4 + ] in the space between the probe and the retinal surface increased to over 0.1 m m [NH 4 + ] during light stimulation.…”

Section: Discussionmentioning

confidence: 99%

A glia–neuron alanine/ammonium shuttle is central to energy metabolism in bee retina

Coles

Martiel²,

Laskowska

2008

The Journal of Physiology

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It has been proposed that glial cells may supply carbon fuel to neurons and also that there are fluxes of ammonium from neurons to glia. We have investigated both these proposals in Apis retinal slices, in which virtually all the mitochondria are in the photoreceptor neurons. Normally the superfusate contained no substrate of energy metabolism; addition of glucose or alanine did not increase oxygen consumption (Q O 2 ), confirming that the neurons received adequate substrate from glycogen in the glia. + ] e in 0 Cl − . These results strengthen the evidence that in superfused retinal slices, glucose is metabolized exclusively in the glia, which supply alanine to the neurons, and that ammonium returns to the glia. They also show that another fuel (perhaps lactate) can be supplied by the glia to the neurons.

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“…In (10), R stands for H and Me. As it can be observed, there is a proton exchange (in this case we can discuss about Bronsted -Lowry acid and bases) and the presence of adsorbed water is a sine qua non condition for dissolving and diffusing the analyte into the interfacial region.…”

Section: Hsab Theory Employed As a Sensing Layer Selection Toolmentioning

confidence: 99%

“…There are many principles and methods described in literature for measuring ammonia. Besides conducting polymer gas detectors, 8 catalytic sensors, 9 spectrophotometric and other optical devices, [10][11] chemiresistive-based sensors employing semiconducting metal oxides (MOX) as sensing layers were also widely used in the last decades. 12 These types of sensors are typically operated at elevated temperature, usually more than 400 °C.…”

Section: Introductionmentioning

confidence: 99%

Nanostructured Semiconducting Metal Oxides for Ammonia Sensors. A Novel HSAB Sensing Paradigm

Serban

Buiu²,

Cobianu³

et al. 2018

ACSi

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The paper demonstrates how the Hard-Soft Acid Base (HSAB) theory can be used as a valuable criterion in the selection process of semiconducting metal oxides (MOX) suitable as sensing layers for ammonia detection. Six different cases of ammonia detection performed by chemiresistive sensors employing MOX and related nanocomposites as sensing layers are identified and discussed. The role of HSAB as an efficient selection tool for appropriate sensing layer (any type of gas), is further reinforced by analyzing and discussing literature results on MOX-based trimethylamine sensing layers. By analyzing the operation of a fiber-optic ammonia sensor, we demonstrate that the HSAB principle can be also successfully applied to the selection of sensing layers for detectors employing other sensing principles, different than the chemiresistive one. Changing the sensing paradigm (i.e., the amino groups-based compounds are part of the sensing layer, rather than part of the analyte), the paper shows that these types of molecules (polymers, carbon nanotubes, ionic liquids) are appropriate constituents of a CO 2 sensing layer, in full accordance to the HSAB criteria.

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Photon-counting optical-fiber sensor for the detection of ammonia in neurochemical applications

Cited by 7 publications

References 9 publications

Mechanisms of Glutamate Metabolic Signaling in Retinal Glial (Müller) Cells

Mechanisms of Glutamate Metabolic Signaling in Retinal Glial (Müller) Cells

A glia–neuron alanine/ammonium shuttle is central to energy metabolism in bee retina

Nanostructured Semiconducting Metal Oxides for Ammonia Sensors. A Novel HSAB Sensing Paradigm

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